wont stay runnin, real boggy

sphynx.0029

Member
Local time
4:08 AM
Joined
Aug 21, 2009
Messages
45
Location
calera, al
ok i doubt there is anything anyone here can tell me that i have not tried but who knows.
symptoms:

extremely hard to start(clutch is catching fine)
once started it will not stay running, boggs down, have to keep pedaling to make teh engine continue to turn over. holding thrott full while pedaling to make the motor catch while clutched. and have to keep pouring teh thrott to keep the engine barely running.(have tried every carb adjustment known to man).
as far as the carb goes we (al.fisherman and myself) have changed teh intake back to a non-ported(for boost) manni, tried 3 of 5 needle positions, changed and replaced the gasket, checked the float positioning, CHANGED CARBS COMPLETELY, nothing is working from that end and teh issue still persists.
no power when the engine is running, will not carry itself.
and tone sounds too deep to me like it is trying to bogg just running while pedaling. will not stay running on its own.

this is an 80cc HT kit, the very same that Al.Fisherman and myself made the taredown tutorial out of. so we know that everything inside the engine is correctly installed. one note of interest tho.

**NOTE**
during the taredown, we could not save and did not replace the lower jug/cylinder gasket (base gasket). we have made our own but i fear that it is not thick enough. could be part of the issue but im not a mechanic so i would not know.

**Secondarily**
WATCH YOUR HEAD GASKETS!!!!
i originally had a tick/rattle in the engine, (thus the reason for the taredown) come to find out that the ticking was teh SBP Head gasket.
when matched with SEVERAL other head gaskets both original and more SBP gaskets, some of them, the inner cut was not matching to the piston stroke, not perfectly circular, stacked together we found that not only were a couple from SBP uneven, but other originals were too. the piston was hitting the uneven part of the gasket.

it ran fine thru the whole break in and now it is nothing but junk(or at least i am starting to think so, again not a mechanic). i would just like it to run. i can get teh rest. or does it just need to R.I.P?
 
Last edited:
Does it have resonable compression when you pedal start it?

Also turn the fuel tap off and try starting. If it suddenly takes off after a while it may be your main jet is somehow now too big?

I've had to close my main jet up (solder & redrill) as the standard jet was way too rich and it four stroked constantly.

Got good spark? Could be that as well.

Good luck!
 
Also remember that if you see a spark, it may not be sufficient for proper combustion

I live up in the cold, and thing absolutely will not start because my CDI loses 90% of power in cold

Ordering a new one soon
 
Tried to pull start with my bike. Would start, but not for long
Compression 150psi. Compression tester installed and pulling with my bike
Changed out CDI with new one
Installed my carburetor on his bike
Installed his carburetor on my bike...Ran fine
Changed to a NEW NGK plug. Gap at both .025 and .030

Going to change coil and install my plug next.

I've worked on hundreds on engines and have never been stumped as this one has me.

OK
it has intake..fuel
good compression
no muffler so has exhaust
to me it has to be electrical.

Some of the things we did to it. Shaved head and cylinder, piston hitting head and made base gaskets. Used folder files (not from PC but the ole fashion ones...lol)..we have three on all sealed with Indian Head sealer. We have 2 head gaskets both copper coated. Installed a boost bottle but since made inoperable to eliminate possible problem. Disconnected kill switch.

Before the base gaskets were installed the engine was running ok, but the problem we had was that the piston was hitting the head gasket. This was the engine I tore apart and made photos of. I'm wondering if the base gaskets are screwing up the intake/exhaust cycle????
 
just a note of interest, Al.fisherman is my dad and we rork on this together, so, to eliminate any confusion, any posts that he makes on this subject are not suggestions. they are things we have done to try to repair the issue.
thanks

sphynx
 
The only way the base gaskets could stuff it up is if they block the transfer ports but you seem to know what you're doing so scrub that one!

Tricky! I think you're right- you've replaced most of the components so it must be coil or winding?

I'm guessing you've checked/swapped the plug wire and cap?
 
The only way the base gaskets could stuff it up is if they block the transfer ports but you seem to know what you're doing so scrub that one!

Tricky! I think you're right- you've replaced most of the components so it must be coil or winding?

I'm guessing you've checked/swapped the plug wire and cap?

Done, when we installed the NEW CDI I keep in stock.

Friday 2pm
Think I figured out WTF was going on. We pulled the bike (towed) to do a compression test yesterday. Seems that at any speed above a fast idle the compression is good. BUT at a idle the compression is too low to accommodate the engine.
 
Last edited:
Ok here is another part of the puzzle.
my engine gets good compression at high RPM. but not enough at low RPM to get fuel from the crankcase to the top of the piston for combustion.

i am thinking we will next change out the piston and check inside the cylinder to make sure that there is nothing of note there to find.
any other suggestions would be welcome. thanks to all for teh assistance.
 
tried 3 of 5 needle positions as stated in orginal message, even changed carb from non running bike and put it on another bike, works fine, took carb off good bike put on non running bike only to find...guess what, still not working, i am thinking it is in teh motor.. thanks tho
 
Back
Top